Add completable wrapper for Zod schemas

src/server/completable.test.ts

@@ -0,0 +1,46 @@
+import { z } from "zod";
+import { completable } from "./completable.js";
+
+describe("completable", () => {
+  it("preserves types and values of underlying schema", () => {
+    const baseSchema = z.string();
+    const schema = completable(baseSchema, () => []);
+
+    expect(schema.parse("test")).toBe("test");
+    expect(() => schema.parse(123)).toThrow();
+  });
+
+  it("provides access to completion function", async () => {
+    const completions = ["foo", "bar", "baz"];
+    const schema = completable(z.string(), () => completions);
+
+    expect(await schema._def.complete("")).toEqual(completions);
+  });
+
+  it("allows async completion functions", async () => {
+    const completions = ["foo", "bar", "baz"];
+    const schema = completable(z.string(), async () => completions);
+
+    expect(await schema._def.complete("")).toEqual(completions);
+  });
+
+  it("passes current value to completion function", async () => {
+    const schema = completable(z.string(), (value) => [value + "!"]);
+
+    expect(await schema._def.complete("test")).toEqual(["test!"]);
+  });
+
+  it("works with number schemas", async () => {
+    const schema = completable(z.number(), () => [1, 2, 3]);
+
+    expect(schema.parse(1)).toBe(1);
+    expect(await schema._def.complete(0)).toEqual([1, 2, 3]);
+  });
+
+  it("preserves schema description", () => {
+    const desc = "test description";
+    const schema = completable(z.string().describe(desc), () => []);
+
+    expect(schema.description).toBe(desc);
+  });
+});